Priming Completed

Due to choosing the wrong filler for the numerous pin holes on the fiberglass parts I am not yet done with painting. In fact, I might not even be done with priming yet but at least I am getting there.
So what was wrong with the filler? I chose Stewart EkoFill grey (which also has UV protective properties) after my good results with their paint system. The EkoFill did turn out to be a nightmare to work with. The previous, somewhat older, can had gone bad and I received a fresh one right on Friday before the big paint weekend.
The EkoFill went on ok. The stuff is very watery and I did not feel good about spraying this as I expected it to just run off. So I used a foam brush as recommended for fabric. Well, the foam brush caused foaming of the EkoFill and it was impossible to completely remove the foam from the surfaces. Once dried I intended to sand the surface smooth but it turned out that sanding EkoFill is near to impossible to do.

It looked good when the first coats had been applied though:

The stuff has a rubbery consistency and dulls open coat sandpaper in a matter of 1-2 minutes. After 3-4 minutes the dull sandpaper does not cut anymore and just peels off little pieces of rubber similar to using an eraser. It took me 4 hours of tedious manual sanding wasting 3 sheets of 320 grit sandpaper and ending up with a not so pristine surface as I had wished for.
The episode was not over yet though. The EkoFill also did not fill the pinholes as I could not build up enough material to bridge them. This is due to being so watery and unsandable which made me not wanting to go through this more than once.

This is how it looked after the sanding episode:

The coat was super thin and it needed more to really get a UV protection. However, Latex paint also has a good UV protection and so I decided to leave it as is and to apply the S-W primer. I watered the primer down to a consistency that I was used to for the paint gun. That was about 20-25% water added to the primer. The primer did not mind but when I applied a stroke with the foam brush I saw that the EkoFill coat repelled the diluted primer so there was no way I could spray this. I had to apply a first coat of undiluted primer with the brush to get it to stick.

I built up the 7'x7' greenhouse that I had found on eBay to get a clean environment for the upcoming spraying.

I put the pieces inside and started applying the first primer coat with the foam brush.

I applied a few more coats with the brush to make sure the EkoFill was well covered before I got to spray the primer tonight for two coats on all 3 pieces.

I will let this sit to dry over night and then check tomorrow if it needs more. I hope it will be sufficient and I can sand this to prepare it for the paint coats.
BTW, I used Floetrol 10% and another 10-15% of water to dilute the primer which worked fine the HF HVLP gun.